This reads a little like saying "you are competent at chess when you know all the moves the pieces can make"
In Chess, knowing your opponent's available moves might make the difference between an absolute beginner and a 300 rated player
Knowing some opening theory might make the difference between 300 rating and 1000 rating
But I don't know that I'd call a 300 rated player 'competent', or even say that they 'know how to play' versus 'know the rules of Chess'
It's consistency in knowing what are good options and what are likely choices that makes a competent/good/great player in any game (most fighting games are perfect information, too!)